Centerless grinding machine



Sept. 9,1947.

A. SCRlVENiER 2,427,024

CENTERLESS GRINDING MACHINE Filed Sept. 29, 1944 4 Sheets-Sheet 1 IIII p 9, 194?. A. SCRIVENER 2,427,024

CENTEBLESS GRINDING MACHINE Filed Sept. 29, 1944 4 Sheets-Sheet 2 III, 4

Sept. 9, 194?. A. SCRIVENER CENTERLESS GRINDING MACHINE Filed Sept. 29. 1944 4 Sheets-Sheet 3 w a R hi 4 8x 1 k//// Patented Sept. 9, 1947 CENTERLESS GRINDING MACHINE Arthur Scrivener, Birmingham, England,

or to Landis. Machine Company,

assignayneslioro,

Pa., a corporation of Pennsylvania Application September 29, 1944, Serial No. 556,426

16 Claims. 1.

This invention relates to centerless grind n machines of the type wherein the work piece is not mounted to rotate between fixed centers but is supported by a plate or work rest positioned in a grinding throat formed between adjacent peripheral surfaces of a grinding wheel and a re ulating or control wheel. Examples of such a grinding machine in which the control or regulating wheel, in addition to rotating the work piece in contact with the grinding wheel, has certain feeding and ejecting functions are disclosed in United States Patents Nos. 2,091,655 and 2,346,- 851 and in British Patents 449,883 and 556,841. However, practical application of the work control or regulating wheel in these patented machines has been found difficult for various reasons,'and it is the general object and purpose of my present invention to provide a novel construction and cooperative assembly of the several machine elements whereby such dimculties will be efiectively obviated.

Another object of the invention is to provide simple and novel means for manually operating the oscillating control or regulating wheel for the purpose of introducing the work piece into the grinding throat and for permitting its removal therefrom.

Another important object of the invention is to provide a means for interchangeably connecting the control wheel with the manual or motor operated means, the latter to be used for the continuous drive of said control wheel in truing or dressing its peripheral surface.

An additional object of the invention, particularly desirable in the finish grinding of roughly pre-formed screw threads, is to provide means cooperating with the control wheel, as the work piece is moved thereby to grinding position on the work support, whereby said means engages the work piece to accurately position the threads thereof relative to thread forming ribs provided upon the periphery of the grinding wheel.

The inventioin has for a further important object the provision of a control or regulating wheel having spaced means adapted to be selectively positioned relative to the work support for feeding work pieces of relativel diflerent sizes to grinding position on the support, and arcuate peripheral surfaces adjoining said work feeding or positioning' means which are of relatively different circumferential extent, so that when the'control wheel is oscillated a definitely predetermined degree of rotation is imparted to the work piece which is the same for work pieces of all sizes.

Still another object of the invention is to provide a Very simple form of clutch means for releasably connecting the manually operable means with the control wheel whereby a selected peripheral section of said wheel, in accordance with the size of the work piece. may be eifectively utilized in the grinding operation.

It is also an important object of the invention to provide a novel mounting and adjusting means for the control or regulating wheel and work support whereby said wheel and support may be adiusted in very small increments with respect to the opposed periphery of the grinding wheel, so as to accurately control the final diameter oi the work piece.

Still another object of the invention is to provide an improved mounting and arrangement of a work rest supportin slide with respect to the grinding and regulating wheel and means where. by said slide may be independently adjusted to accurately position or locate the work receiving surface of said work rest within the grinding throat.

It is also the aim and purpose of my invention to provide a centerless grinding machine as above characterized comprising a very compact assembly of structurally simple cooperating elements which will be highly eflicient in functional operation, as well as rugged and durable, so that maintenance expense will be reduced to a minimum.

With the foregoing and other subordinate obiects in view, the invention comprises the improved centerless grinding machine and the construction and relative arrangement of its several parts as will be hereinafter more fully described.

illustrated in the accompanying drawings and subsequently incorporated in the subioined claims.

In the drawing, wherein like reference characters designate corresponding parts throughout the several views and in which I have shown one preferable embodiment of my invention:

Figure 1 is a partial front elevation of the machine showing the control or regulating wheel positioned relative to the start of the grinding operation;

Figure 2 is a fragmentary vertical section taken substantially onthe line 2-2 of Figure 3, showing the position of the control wheel relative to the work at the end of the grinding cycle;

Figure 3 is a transverse sectional view taken substantially on the line 3-3 of Figure 1;

Figure 4 is a detail side elevation of the control wheel clutch operating cam;

Figure 5 is a longitudinal sectional view taken substantially on a vertical plane which includes work support at the form of clamping device indicated at 38. holder 36 extends vertically downward from the slide 34 and in the lower end thereof the dia- I the axis of the feed screw for the adjustable control wheel head;

Figure 6 is a transverse sectional view taken substantially on the line 6--6 of Figure and Figure 'I is a fragmentary vertical sectional view taken substantially on the line 'I''| of Figure 5.

. atively mounting said control wheel on the head 28 will be hereinafter more fully described. The grinding wheel 24 is power driven and continuously rotated in a clockwise direction while the work control wheel 38 is adapted to be oscillated in the grinding operation at comparatively low speed.

Upon the upper end of the head 28 a housing 32 is suitably mounted for longitudinal sliding movement. This housing at one end supports the cross slide 34 which carries the dressing tool holder 36 secured to the slide 34 by a suitable The mond or other form of wheel dressing tool 48 'is suitably mounted. The sliding movement of housing 32 on the control head is effected by the hand wheel 42 which operates conventional screw mechanism (not shown) contained in the top of the control head 28. As will be understood, by

slidably adjusting the housing 32 relative to head 38 for properly dressing its peripheral surface.

Referring now to Figure 2 of the drawing, a

4 plate 44 is supported upon the slide 26 and pivotally connected thereto intermediate its ends by the pin 46. This plate is formed with the female parts of a slide assembly, the male parts of which are formed upon the secondary slid 48. As seen in Figure 3 of the drawing, a gib 58 is interposed between one of the side faces of the plate 44 and opposed side face of the slide 48. Adjustable set screws 52 are provided to retain said gib in position and to also properly adjust the same relative to the plate 44 for the purpose of compensating for wear between said plate and the slide 48.

The slide 48 at one end thereof is formed with an upwardly extending part 54 at each side of the regulating and grinding wheels. These parts are provided with the upwardly opening slots or bifurcations 56 which receive opposite end portions of the work support 58. Each end of said work support is supported in a bracket member 68 extending downwardly into the slot 56, said member at its lower end having an angularly extending lug 62 upon which the lower edge of the support 58 is engaged. At its upper end the bracket member has a lug 64 extending laterally in the opposite direction from lug 62 above the part 54 at one side of the slot 56. This lug 64 carries an adjustable screw 65 which bears at its lower end upon the top surface of the part 54. It will be understood that while only one of these brackets 68 is illustrated in the drawing, the other 'bracket member, located at the opposite end of the support 58 to that shown in Figure 2, is of the same construction. After these brackets have been vertically adjusted by means of the screws 65 to position the upper edge of the support 58 relative to the grinding throat, they are rigidly fixed in such adjusted positions by means of the screws 66 threaded in the part 54 which engage the bracket members at their inner ends. Thus by adjustment of the screws 66 the support 58 is securely clamped against one side wall of the slot 56 and said support and the bracket members 68 securely held against vertical movement relative to the slide 48. As herein shown the support 58 has its upper work receiving surface 68 trans- .versely inclined downwardly from the periphery of the grinding wheel 24 toward the periphery of the control wheel 38.

Below the control wheel 38 the slide 48 is provided with the longitudinal extension I8, the upper side of which is grooved or channeled as at I2 to accommodate the lower portion of the wheel 38. A rod I4 has a threaded connection 16 with the end of the slide extension I2, the other end of said rod being threaded into the inner end of a tubular shaft I8 extending through an opening 88 provided in one side wall of control wheel head 28, where it is rotatably mounted in an external bracket member 82 secured to the wall of said control head by suitable screws indicated at 84 extending through elongated slots in the bracket. Hand wheel 86 is secured to the extremity of the shaft I8 by means of the key 88 and lock nut 98. It will thus be obvious that by rotating the handwheel 86 the slide 48 is longitudinally moved relative to the control wheel head 28 and slide 26 to horizontally position the upper work receiving surface 68 of the work rest 58 in the grinding throat between the proximate peripheral surfaces of the grinding Wheel 24 and the control wheel 38. The pivot 46 permits of a slight adjustment of slide supporting plate 44 to accurately position the upper surface of work rest 58 in parallel relation with the axes of wheels 24 and 38.

Referring now to Fig. 3 of the drawing, it will be seen that the control head 28 has a front end portion 92 formed to provide a housing for the control wheel 38 and the slide 48. Extending rearwardly from said housing the head 28 is formed with a cylindrical bore 94 each end of which contains a bushing 95, in which the shaft or spindle 98 is journalled. The rear end'portion I88 of this shaft is of reduced diameter to receive a suitable type of anti-friction thrust bearing I82, said bearing and the shaft being retained in correct axial position by means of the cap member I84, belt sheave I86 keyed to the shaft end, and the lock nut I88. The other or forward end of the bore 94 is sealed against the entrance of cooling medium, grinding dust or other foreign matter by means of the cap member II 8.

Forwardly of the cap member II8 the shaft 98 is provided with a sharply tapered portion II2 which terminates in a threaded extension II4 of reduced diameter. A hub sleeve I I6 has a tapered bore to receive the shaft portion H2 and is secured thereto against relative rotation by the key II8. At its rear end the sleeve I I6 is formed with a diametrically enlarged portion I28 provided against the adjacent side face of the wheel. An annular member I26 is telescopically fitted over the other end of the hub sleeve H6 and within the opposite end of the opening I24 of the control wheel, said member having the flange I26 for abutting contact against the front face of said wheel. This member I26 is connected with the part I26 of the hub sleeve by means of tie bolts I66 having threaded connection with said part and whereby the hub sleeve and member I26 are rigidly connected against relative rotation for substantially 160 of the circumference of the bushing (see Figure 4). A shaft I92 journalled in the bushing I66 has a radially protruding pin or stud I94 fixed therein and engaged in the cam slot I96 of the bushing. The inner end ofshaft I92 is connected to the shaft I46 by a reduced end section of the shaft I92 having its-terminal head I96 positioned in an axial recess I96 formed in the enlarged end I64 of the shaft I46. A suitable thrust bearing 266 is positioned between the head I96 and the base of the recess, and said and with their flanges I22 and I26, respectively,

intight clamping contact with the opp site side faces of the control wheel 96. Axial movement of the hub sleeve and therefore of the member I26 and control wheel 66 relative to the part N2 of shaft 96 is prevented by the lock nut I92 threaded upon the end II4 of the shaft in abutting contact with the front end of the hub sleeve H6.

The member I26 is also formed with a forwardly projecting annular flange I 94 provided with the open ended slots or recesses I96, circumferentially spaced apart to constitute the female element of a clutch mechanism to be presently more fully described.

The front side of the wheel housing 92 of the head 26 is closed by the flanged cover member I96, hinged to said head along one vertical edge of the cover as at I66. In the normal operation of the machine this cover is secured in'its closed position by means of the screws or bolts I42. The cover wall is provided with a circular opening I44 in axial alignment with the shaft 96. This opening contains the bushing I 66 in which the short shaft I46 is joumalled. To the rear end face of this shaft and projecting radially therefrom the clutch dog I66is rigidly fixed by means of the screw I62 and is adapted for engagement in any one of the grooves or 'slots I66 in the flange I64 of the member I26 so as to thereby effect the unitary rotation of the shafts I66 and 96. To an enlarged cylindrical head I54 formed on the end of shaft I66 externally of the cover I38 the end of a radially and upwardly extending handle member I56 is fixed by means of the pin I58.

Below said handle and to the front of the cover I96 9. housing I66 is secured by means of suitable screws I62, the front side of the housing being closed by the cover plate I66 attached thereto by screws I66. The top wall of this housing is formed with an integral upward extension I66 which is forwardly spaced from the end of the shaft I66. This extension has an arcuate perimee ter provided with the vertically disposed flange I16 having the arcuate slot I12 therein. The stop lug I16 extending rearwardly from this flange I16 at one side of the handle member I 66 has a threaded shank extension I16 disposed through the slot I12 to receive the nut I16 contacting the front face of the flange I16, whereby said stop member I'M may be securely fixed in a predetermined adjusted position lengthwise of the slot I72. This stop lug I14 serves to limit the counter-clockwise movement of the handle member I56. Movement of said handle in the opposite or clockwise direction may be variabl limited by means of the adjustable stop screw I66 vertically positioned in a bracket lug I62 on the top wall of the housing I66 and secured in adjusted position by means of the lock nut I66.

Housing extension I66 is formed with a cylindrical opening in alignment with the shafts I46 and 96. Within this opening a flanged bushing I66 is secured by means of screws I66. This bushing is provided with a helical slot I66 extending head and hearing are retained within th recess by means of the cap plate 262 secured to the end I64 of the shaft I46 by suitable screws 264.

Forwardly of the housing extension I66 a cam disk 266 is fixed to the shaft I92 by the key 266, said cam disk being restrained against axial movement by a shoulder formed on the shaft I92 and the nut 2I6 threaded uponthe end of said shaft and engaged against the front face of the cam disk. This cam disk is provided with a radially disposed handle member 2I2 normally extending substantially horizontally therefrom, and the disk 266 at the lower side thereof is formed with the flattened surface 2I4, disposed in a plane substantially parallel to the axis of the handle The remaining peripheral surface of the cfllszk 266 is substantially concentric with the shaft From the above description it will be readily seen that upon rotation of the handle member 2I2 in a counter-clockwise direction from the position shown in Figure 1, cam disk 266 and shaft I62 will be rotated to cause pin I96 to coact with the walls of the helical slot I96 in fixed bushing member I66. thereby causing an outward axial movement of the shaft I62, resulting in a similar outward axial movement of the shaft I68 so that the clutch lug I56 will be withdrawn from the slot or recess I66 in member I26, thereby disconnecting the shaft I66 from the shaft 98.

When the handle 2 I 2 is in its normal horizontal position, the flat face 2M of the cam disk 266 has bearing contact upon the convex upper end of a follower member 2I-6 which is vertically movable through an opening 2I6 in the top wall of the housing I66. The lower portion of this member has a threaded bore 226 with which the upper threaded end of a rod 222 is adjustably connected and locked in adjusted position by the nut 226. The lower end of said rod is movable through the opening 226 in the bottom wall of the hous ing I66 and adjacent thereto is provided with a transversely fixed pin 226 extending beyond opposite sides of said rod.

A lever 266 is pivoted intermediate its ends as at 232 between opposite side walls of the housing I66. One end of this lever is forked to straddle the rod 222 and each of the fork arms has a slot 236 therein to receive one end of the pin 226. In the other end of lever 236 a roller 236 is rotatably mounted and has upward bearing contact against the lower end of an actuating member 266 for the switch 246 controlling the operation of an electric motor having driving connection with the sheave I66 fixed to the rear end of the shaft 96. This switch actuating member is normally urged to circuit opening position by the spring 242. Therefore it will be understood that when the handle 2I2 is operated as above explained to disengage the clutch means connecting manually operable shaft I48 with the control wheel shaft 96 the cam surface 2I4 c0- acts with the upper end of follower 266 to force the rod 222 downwardly, thereby rocking lever 238 and actuating the operating member 238 for switch 248 to close the motor energizing circuit. Shaft 88 and the control wheel 38 will then be continuously rotated in one direction at relatively high speed for the purpose of truing or dressing the peripheral surface of said wheel by means of the tool 48. In this manner it is apparent that the motor can not he accidentally energized to drive the control wheel at high speed, while the manually operable means for oscillating said wheel at relatively low speed in the grinding operation remains connected with the shaft 88.

Referring now more particularly to Figures 1 and 2 of the drawing, it will be noted that one side face of the work support 58 below the work receiving top surface 68 thereof is of arcuate concave form, as shown at 244, and in opposed, substantially concentric relation to the periphery of the control wheel 30.

The control or regulating wheel 30 is of unusual form, and as herein shown is provided with a plurality of circumferentially, non-equidistantly spaced pockets or recesses. In the present instance I have shown five of these work receiving pockets designated 246, 2148, 250, 252 and 254, respectively. It is to be noted that these rccesses are of non-uniform size and depth, each recess having one side wall thereof extending in substantially radial relation to the axis of the control wheel, as indicated at 255, while the other side wall of each recess is obliquely inclined as at 258 in divergent relation from the opposed wall 256 to the peripheral face of the wheel. It will further be noted that the arcuate peripheral surface portions 250 of the control wheel extending between the side walls 258 and 258 of successive work receiving pockets or recesses are of different or unequal circumferential lengths. The spacing of the recesses and the length of the peripheral surface sections '260 is so calculated and designed that in the grinding of work pieces of various different sizes in every case the work piece will be rotated upon the upper surface 68 of the work support 58 for only slightly more than a single revolution. It is found that in many cases, and'particularly in the grinding of screw threads, this limitation upon the rotative movement of the work piece in contact with the face of the grinding wheel is desirable in the interest of accuracy in the final diameter of the work piece. In the present instance I have shown such a work piece at 262 having screw threads rough- 1y pre-formed thereon. Therefore the peripheral surface of the grinding wheel 24 is provided with circumferentially continuous V-shaped ribs, indicated at 264, in immediate succession to each other across the surface of the wheel for the purpose of accurate finish grinding of the pre-formed threads on the work piece.

In operation the work piece is inserted into one of the control wheel pockets 248, 250, 252 or 254 of selected size when said pocket is disposed in adjacent opposed relation to the arcuate surface 244 of the work rest 58, as indicated in dotted lines in Figure 1 of the: drawing. Of course the work piece will roll by gravity down the inclined edge face 258 of the work receiving pocketand into contact with the arcuate surface 244 of the work support. When handle member I56 is now rotated from its position against the stop I14, in a clockwise direction, the wheel. 30 will be manually oscillated and the edge face 258 of the control wheel pocket will push or roll the work piece 252 upwardly over the work support surface 244 until the work piece eventually comes to a position of rest upon the upper transversely inclined surface 68 of the work support, as shown in full lines in Figure 1. As the work piece moves upon the surface 68 the screw threads thereof are engaged by a vertically positioned finger 256, the lower end of which substantially conforms to the cross sectional profile of the screw threads. This finger insures the correct positioning of the thread profile on the work piece with respect to the ribs 264 on the grinding wheel 24. The pocket 246 is used only for the discharge of a work piece after surface 268 between this pocket and pocket 248 moves out of contact therewith. It will therefore, be understood that the short peripheral surface 260' between pocket 246 and pocket 254 does not function to rotate a work piece on the support 58.

The locating or positioning finger 286 is resiliently and rockably mounted rearwardly of the wheels 24 and 30 for universal adjustment relative to the work piece so as to properly coact with work pieces of various diameters having screw threads of different pitches and helix angles. Since this adjustable mounting of the locating finger is fully shown and described in United States Patent 2,091,655 above referred to, it need not herein be further described in detail.

A manual oscillation of the control wheel 30 in a clockwise direction is continued by operation of the handle member I56, the arcuate peripheral surface 260 moving upwardly from the position shown in Figure 1 of the drawing rotates the work piece upon the surface 68 of the work support and urges the same into contact with the surface of the grinding wheel 24. After the work has thus been rotated in the grinding throat for somewhat more than one complete revolution the peripheral surface 260 will then be in approx imately the position shown in Figure 2 of the drawing, so that upon further oscillating motion of the wheel in a clockwise direction the work piece will roll downwardly off the surface 68 of the work support 58 into the next succeeding pocket of the control wheel 30, from which the finished work piece is then removed. Rotation of the control wheel is now reversed until the selected work receiving pocket is again located at the starting position shown in dotted lines in Figure 1 to receive a new work piece, whereupon the work grinding cycle is repeated. Thus only two of the work receiving pockets or recesses in the control wheel 30 and the arcuate peripheral surface extending between them are used in the grinding of any one size of work piece. It will be seen that by means of the present invention several different sizes of work pieces can be ground and it is not necessary to change the control wheel 30 for each size of work. By proper adjustmentpf the stops I14 and I the operation of the handle member I56 may be properly limited to control the angle through which the wheel 30 is oscillated in accordance with the particular size of the work piece being ground and the particular arcuate peripheral section of the control wheel 30 which cooperates therewith. By releasing the clutch connection between the shaft I48 and the shaft 98 in the manner above explained, after first disabling or interrupting the driving connection between the motor and shaft 98, the control wheel 30 can then be manually adjusted to dispose a selected work receiving pocket and arcuate peripheral section 260 of said control wheel in working position relative to the support 58.

I have also provided means whereby the control wheel 38 may be adjusted relative to the aeaaoee grinding wheel to accurately predetermine the I width of the grinding throat in accordance with the known diameter of the roughly pre-formed work piece to be ground. This adjusting mechanism will now be described with more particular reference to Figures 5, 6 and 'Z of the drawing. As herein shown the machine base 20 is provided with a longitudinal opening 288 beneath the control wheel head 28 which opens upon one side of said base. A bracket member 2710 is secured to said side of the base 20 by means of suitable screws, indicated at 212, and has a part thereof extending into the opening 268. A plate 2'14 is detachably secured to the top of this bracket by screws 21B and extends into the opening 268 at the upper side thereof to efiectively close the same and exclude foreign matter.

A shaft 278 is journalled in the bracket 210, a thrust bearing 2% being interposed between the inner end of said bracket and a shoulder 282 on the shaft. This shaft is formed with a feed screw section 283 having threaded engagement in a flanged nut 284 secured in a bracket member 286 by means of screws 288, said bracket member being secured to the slide 26 of the control wheel head 28 by the screws 290. It is therefore clear that rotation of the shaft 218 will impart longitudinal movement to the head 28 and control wheel 30 relative to the base 20. Thus the periphcry of the wheel 30 may be properly positioned relative to the periphery of grinding wheel 2% to provide a grinding throat for receiving .work pieces of various sizes. Lost motion between the shaft 218 and the nut 288 is eliminated by means of the spring 292, which bears at one of its ends against bracket 286 and at its other end against plate 296 on the end of the shaft. A cap member 298 has a sleeve extension telescoped on this end of said shaft and a thrust bearing 2% surrounds said sleeve between the cap and the plate 2%. This assembly is retained on the end of the shaft M2 by means of the screw 3B0 extending through the cap 295 and threaded into, the end of the shaft.

The outer endportion of bracket member are is provided with a bore 392 in the inner end of which the thrust bearing 3% is retained by the bushing 305, said bushing being keyed to shaft W8, as shown at 308, and held against axial displacement by nut 3w threaded on the outer end of said shaft and locked thereto by the radially adjustable screw 3!? carried by said nut and urging the plug or pin 3% into binding contact with the threaded end of the shaft.

Adjacent the end of the bracket 21!] the bushing 30B i externally formed with the flange 3H5. A worm wheel 38b loosely surrounding the bushing 306 has contact at one side thereof with the outer face of the flange tit. The hub 322 of a large hand wheel 320 is also mounted upon the bushing 306 at the outer side of the worm wheel 318. To the inner end of the hand wheel hub a fiber washer 32B is secured by means of suitable screws 326. This washer has a. tapered peripheral face for frictional contact with a similarly tapered circumferential face of the recess 328 formed in the outer side face of the worm wheel M8. The handwheel 320 is provided with a suitable form of hand grip 33!! whereby it may be operated, and is restrained against rotative movement onthe bushing 308 by the key 332 fixed to the bushing and extending into a keyway in the inner face of the wheel hub 322 and it will be noted that this keyway is of slightly greater with suitable l length than the key 332 so that the wheel hub may move axially outward on the bushing 306.

The terminal portion of the bushing 306 beyond the wheel hub 322 is threaded to receive the nut 33-6 in which the ends of a plurality of ansularly disposed handle members 336 are threaded.

as will be noted from reference to Figure 5 of the drawing, when the nut 338 is threaded inwardly on the end of bushing 306 to clutch the handwheel 326 to the worm wheel BIB by means of the fiber washer 326, the outer face of said nut is spaced from the opposed face of the lock nut Bill on the end of the shaft 278. In this position of the parts, the worm wheel are, handwheel 320, bushing 306, and shaft 218 are rotated as a unit by means of the worm 333 onclosed within the lower 3% for said worm and worm wheel, aid housing being secured to a part of the bracketmember 270 by suitable screws as indicated at 362. An upwardly and outwardly inclined arm-3M is secured to the top of said housing by a screw M6 and at its upper end is formed with an index pointer 3% extending over the periphery of the handwheel 320, which has suitable indicia engraved thereon to indicate the extent of rotation of said handwheel.

From reference to Figure 6 it will be seen that the shaft 350 of the worm 338 is journalled in suitable bearing bushings 352 in opposite ends of an elongated horizontal extension the housing 340. At the outer end of one of these bushings thrust bearing 35d is mounted on a reduced end portion of the shaft 35d and said bearing is retained in position by the cap plate 356 secured to the wall of the housing by screws 358. Adjacent the outer end of the other bushing 352 the worm shaft 350 is formed with the flange 38d and the diametrically reduced extension 362. Upon this reduced portion of the shaft, at the outer side of the flange 369, the thrust bearing 36d is retained in the end of the housing extension by the cover plate 366 attached to the housing by mean of screws 368. At the outer side of plate 386 a disk are is fixed to the end portion 362 of the worm shaft by the adjustable screw 312 and the locking pin or plug 315, The Worm shaft 350 has a further reduced threaded extremity 316 projecting from the shaft portion 362 on which the hub portion of the handwheel 318 is keyed as at 380 and held against axial movement thereon with respect to disk 37s by means of the nut 382. The peripheral face indicia readable with relation to an index line on the periphery of the cover plate 366 to indicate the extent of rotation of the worm shaft 358. a

From the above description it will be understood that in making the initial general adjustment of the head 28, control wheel to and Work rest 58 relative to the grinding wheel 24, the nut see is rotated in a direction to move the same outwardly on the end of the bushing306 and against the lock nut did so that the hub of the handwheel 320 may move outwardly on said bushing to release the frictional pressure of clutch washer 32-6 on the worm wheel 3I8. Therefore when the handwheel 320 is rotated the bushing 3I6 and shaft 218 will rotate as a unit therewith to ionitudlnally move the head 28 and wheel 30, while the worm wheel M8 and worm 338.1-emain stationary. The work support 58 may then be independently adjusted between the grinding and control wheels by operating handwheel 86 to move the slide 48 relative to the slide 26.

portion of the housing of the disk are is engraved For the final adjustment of the control wheel 30 in small increments, nut 334 is threaded inwardly to the position shown in Figure 5, whereby the worm wheel 318 is securely locked on the bushing 30! between the fiber washer 324 on the hub of the handwheel 320 and the flange'3l6 on said bushing. When the handwheel 318 is now rotated worm 338 cooperating with worm wheel 3 l 8 transmits unitary rotation to said worm wheel, bushing 306, handwheel 320, and shaft 218. Thus the shaft will be very slowly rotated to efiect the final desired adjustment of the control wheel 30 with respect to grinding wheel 24 and exactly predetermine the width of the grinding throat in accordance with the diameter of the work piece to be ground. Also, by operating the latter adjusting means during the grinding operation the control wheel may be moved toward the grinding wheel in extremely small increments so that the operator may exercise accurate control over the final diameter of the finished work piece.

From the above it will be evident that I have devised a centerless grinding machine having many novel features which contribute to the economical and eificient operation of machines of this class. While the machine may be employed to advantage in the grinding of various different kinds of work pieces, it is particularly desirable for such operations as require grinding to close limits, such as the grinding of screw threaded work pieces where a high degree of accuracy in the pitch and final diameter of the helical screw threads is an essential consideration. The present invention eliminates the objections to machines of this type heretofore proposed and provides a simply constructed and easily operated grinding machine whereby screw threads on work pieces of a variety of different sizes may be accurately ground with absolute uniformity.

The arrangement of the work receiving pockets in the regulating or control wheel provides means cooperating with the work rest or support for properly introducing the work piece into the 12 {naintenance costs of which will be reasonably The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a centerless grinding machine, a. grinding wheel, a control wheel in peripherally opposed relation to the grinding wheel, having a plurality of circumferentially spaced arcuate surfaces of relatively different lengths, a work support between said wheels with respect to which said arcuate surfaces of the control wheel are adapted to be selectively positioned, and means for oscillating said control wheel comprising a manually operable member, and clutch means for releasably establishing an operative connection between said member and the control wheel.

2. The centerless grinding machine defined in claim 1, in which said clutch means includes complementary clutch elements respectively fixed to the control wheel and said manually operable member, and wherein additional means is provided having a manually operable part connected grinding throat and also for permitting its easy removal upon completion of the grinding operation, while the control wheel sections of relative different arcuate lengths insure proper limitation upon axial rotation of each size of work piece against the face of the grinding wheel so that the metal stock removed during the operation is in the same proportion to the diameter of the work piece for all sizes thereof.

Among other important practical features of the present invention, reference may be made to the means for interchangeably connecting the control wheel to the manually operated means for oscillating said wheel during the grinding operation and for connecting said wheel with a source of driving power for high speed continuous rotation of the wheel in truing or dressing its peripheral surface; simple and easily operated mechanism for properly adjusting the control wheel relative to the grinding wheel to properly control the removal of metal stock from the work piece and insure an absolutely accurate final diameter of said work piece; and the means for adjustably mounting the work rest or support, whereby the upper end of the support which receives the work piece may be properly located within the grinding throat. In general, my present invention provides a highly eificient grinding machine of this type the several parts of which are of simple and durable structural form, capable of expeditious and accurate assembly, and th production and with said member to shift the same and engage or disengage said clutch elements.

,3. In a centerless grinding machine, a grinding wheel, a control wheel in peripherally opposed relation to the grinding wheel, having a plurality of circumferentially spaced arcuate surfaces of relatively difierent lengths, a work support between said wheels with respect to which said arcuate surfaces of the control wheel are adapted to be selectively positioned, and means for oscillating said control wheel comprising a rotatable and axially movable shaft aligned with the axis of the control wheel, a clutch element fixed to the control wheel, a coacting clutch element fixed to one end of said shaft, a manually operable member fixed to the other end of the shaft to oscillate the control wheel in the engaged position of the clutch elements, and means for retaining the clutch elements in engaged or disengaged position, including a manually operable member connected with said shaft to axially shift the same and move the clutch element thereon into or out of engagement with the clutch element on the control wheel.

4. The centerless grinding machine defined in claim 3, wherein said last named manually operable member is a rotatably supported shaft having a part coacting with relatively fixed cam means to axially shift said first named shaft.

5. In a centerless grinding machine, a, grinding wheel, a. control wheel in peripherally opposed relation to the grinding wheel, having a, plurality of circumferentially spaced arcuate surfaces of relatively different lengths, a work support between said wheels with respect to which the arcuate surfaces of the control wheel are adapted to be selectively positioned, power means for continuously rotating said control wheel in one direction, means for oscillating said wheel comprising a manually rotatable shaft and clutch means for releasably connecting said shaft with the control wheel, means including a manually adavpes operable member connected with said shaft for releasing said clutch means, and means actuated in the clutch releasing operation of said member to render said power means efiective to rotate the control wheel.

6. In a mechanism for adjusting machine tools, a slide on which the tool is operatively mounted, a feed screw connected with said slide, said screw having a shaft extension at one end, a bushing fixed thereon, a handwheel keyed to the bushing for operating the feed screw to effect major adjustments of the tool slide, a worm wheel loosely mounted on the bushing, said bushing having a shoulder limiting axial movement of the worm wheel in one direction, the opposite side of the worm wheel being recessed, a clutch disk fixed to one end of the handwheel hub, a nut threaded on said bushing coacting with the other end of said wheel hub to axially move the same on the bushing and urge said-disk into frictional engagement with the outer wall of said recess and establish a driving connection between the worm wheel and handwheel and a manually operable worm engaged with said worm wheel, whereby the feed screw may be operated to adjust the slide in small increments.

'7. In a centerless grinding machine, a grinding wheel, a control wheel, said wh'eels being mounted to rotate about spaced axes in periphery opposed relation to form a grinding throat, and said control wheel having circumferentially spaced sections provided with peripheral surfaces of relatively difierent lengths to selectively engage and on said supportin the oscillatory motion of said wheel in one direction. said control wheel being further provided between successive work receiving means with arcuate peripheral surface sections of relatively difierent lengths to urge the work into contact with the peripheral surface of the grinding wheel and impart limited rotation thereto on the support, and means for limiting oscillation of the control wheel after completion of the grinding cycle to position the succeeding work receiving means with respect to the work support to receive the finished work piece.

12. In a centerless grinding machine, a grinding wheel, a control wheel, said wheels being mounted to rotate about horizontally spaced axes in peripherally opposed relation to form a grinding throat, means for oscillating said control wheel with respect to the grinding wheel, a work support in the grinding throat, circumferentially spaced work receiving pockets extending inwardly from the periphery of the control wheel to receive work pieces of different sizes, said pockets bein non-equidistantly spaced apart and adapted to be selectively positioned relative to the work support to cooperate therewith and feed a work piece to grinding position on said support and said wheel having arcuate peripheral surfaces of difierent lengths extending between successive pockets to engage and impart limited axial rotation to the work piece in contact with the peripheral face of the grinding wheel in the oscillatory motion of said wheel in one direction.

rotate work pieces of different sizes in the grinding throat.

8. The centerless grinding machine as defined in claim 7, wherein said control Wheel, between the spaced sections thereof, is provided with means for feeding a work piece int the grinding throat and for receiving the finished work piece therefrom.

9. The centerless grinding machine defined in claim 1, wherein said clutch means includes a clutch element fixed to the control wheel and a coacting clutch element operatively connected with the manually operable member, together with cam controlled means connected with the latter clutch element to move the same into or out of engagement with the clutch element on the control wheel.

10. In a centerless grinding machine, a grinding wheel and a work control wheel, mounted in peripherally opposed relation to form a grinding throat, manually operable means for rotating said control wheel, power means operatively connected with said control wheel for rotating the same at high speed, means for releasably establishing an operative connection between said manually operable means and the control wheel, and means operatively controlled by said last named means in the operation thereof to discon-= nect the manually operable means from the control wheel, to render said power means efiective to rotate the control wheel.

11. In a centerless grinding machine, a grinding wheel, a control wheel, said wheels beingmounted to rotate about'horizontally spaced axes in peripherally opposed relation to form a grinding throat, means for oscillating said control wheel with respect to the grinding wheel, a work support in the grinding throat, said control wheel having circumferentially spaced work receiving means adapted to be selectively positioned relative to the work support and cooperating therewith to feed the work piece to grinding position 13. In a centerless grinding machine, peripherally opp sed grinding and work control wheels forming a grinding throat, a work supporting member in said grinding throat, said control wheel being provided with a plurality of circumferentially spaced arcuate peripheral surface sections of relatively difierent lengths adapted to be selectively positioned relative t said supporting member, and means associated with said wheel and operative thereby in the oscillating motion of the wheel in one direction to feed a. work piece to grinding position on said supporting member in advance of said selected peripheral surface section of the wheel.

14. In a centerless grinding machine, peripherally opposed grinding and work control wheels forming a grinding throat, separate operating means for respectively oscillating the control Wheel at low speed or continuously rotating said wheel at relatively high speed, and means for selectively establishing an effective operative connection between said separate operating means and the work control wheel.

15. The centerless grinding machine defined in claim 14, together with a manually operable means for actuating said last named means to simultaneously establish a driving connection betweenone of said operating means and the control wheel and disconnect the other operating means therefrom.

16. In a centerless grinding machine, a grinding wheel and a control wheel mounted to rotate upon horizontally spaced axes in peripherally opposed relation, a vertically disposed support between said wheels having a work supporting surmove the same upwardly in the rotation of the control wheel to grinding position upon said work supporting surface, whereby after completion of the grinding operation, in the continued rotation 01' the control wheel, the finished work-piece gravitates from said inclined surface of the work support into another or said pockets.

ARTHUR SCRIVENER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Lloyd Apr. 18, 1944 Number Number Number 

